In an uplink and downlink separation technology, when a terminal receives downlink data, the terminal selects a cell corresponding to a maximum downlink signal received power as a serving cell; when the terminal sends uplink data, the terminal selects a cell corresponding to a smallest uplink path loss as a serving cell. In a heterogeneous network system, when uplink or downlink data is transmitted between a terminal and a network side, to maximize a downlink signal received power and minimize an uplink path loss, the uplink and downlink separation technology is used, that is, when the terminal sends uplink data to or receives downlink data from the network side, different wireless communication nodes are used as serving base stations for the terminal.
When the uplink and downlink separation technology is used, uplink coverage and downlink coverage of a wireless communication node are not necessarily same coverage.
For example, for a terminal whose uplink serving node is a micro base station and whose downlink serving node is a macro base station, when the terminal sends uplink data to the micro base station, if hybrid automatic repeat request (HARQ) feedback information sent by the micro base station by using a physical hybrid automatic repeat request indicator channel (PHICH) cannot be received within a specified time, the terminal considers that the micro base station does not successfully receive the sent uplink data and therefore the terminal sends the uplink data to the micro base station again.
For a terminal that is not within downlink coverage of the micro base station, the terminal cannot receive a HARQ feedback message sent by the micro base station, and cannot determine, according to the HARQ feedback message sent by the micro base station, whether to retransmit uplink data to the base station, and therefore, a HARQ mechanism between the terminal and the micro base station cannot work. For example, the terminal sends uplink data to the micro base station, where the uplink data is successfully received by the micro base station, and the micro base station sends, on a PHICH, an acknowledgment indication (ACK) to the terminal. However, because the terminal is not within the downlink coverage of the micro base station, the terminal cannot receive downlink data and downlink signaling from the micro base station and the terminal cannot receive the acknowledgment indication sent by the micro base station, so that the terminal uses, in a corresponding subframe according to a time sequence requirement, a time-frequency resource on which the uplink data is sent at the first time, to retransmit the uplink data. However, the micro base station has successfully received the data, and the micro base station schedules another terminal on the time-frequency resource on which the terminal retransmits the uplink data. Consequently, a conflict occurs when another terminal uses the time frequency resource.